This invention relates to injection molding and more particularly to a heated melt conveying manifold for a multi-cavity injection molding system.
Heated manifolds for distributing melt from a common inlet to a number of spaced outlets are well known in the art. It is also well known that the length and size of the melt passage through the manifold must be equal or balanced and that sharp bends or corners are not acceptable as they can result in decomposition of the melt due to undue stress. An example of a bridging manifold system is shown in the applicant's U.S. Pat. No. 4,761,342 which issued Aug. 2, 1988. The various elongated manifolds were made by the composite plate method described in the applicant's U.S. Pat. No. 4,648,546 which issued Mar. 10, 1987. As can be seen, while they are suitable for many applications, these manifolds have the disadvantage that the portions of the melt passage having the smoothly curved bends necessarily extend in a single plane.
Another example of manifold manufacture which is suitable in some cases is the drill and plug method disclosed in U.S. Pat. No. 4,609,138 to Harrison which issued Sept. 2, 1986. This method has the inherent problem that it is difficult to make the bends in the melt passage sufficiently smooth for high stress applications and materials.